Holt Physics.pdf

Raymond A. Serway

Jerry S. Faughn

Contentsii

Authors

Raymond A. Serway, Ph.D.Professor EmeritusNorth Carolina State University

Jerry S. Faughn, Ph.D.Professor EmeritusEastern Kentucky University

Copyright 2006 by Holt, Rinehart and Winston

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On the cover: The large blue image is an X ray of an energy-saving lightbulb.

The leftmost, small image is a computer model of a torus-shaped magnet that is

holding a hot plasma within its magnetic field, shown here as circular loops. The

central small image is of a human eye overlying the visible light portion of the

electromagnetic spectrum. The image on the right is of a worker inspecting the

coating on a large turbine.

iiiContents

Acknowledgments

ContributingWriters

Robert W. AvakianInstructorTrinity SchoolMidland, Texas

David BethelScience WriterSan Lorenzo, New Mexico

David BradfordScience WriterAustin, Texas

Robert DavissonScience WriterDelaware, Ohio

John Jewett Jr., Ph.D.Professor of PhysicsCalifornia State

Polytechnic UniversityPomona, California

Jim MetznerSeth MadejPulse of the Planet radio

seriesJim Metzner Productions,

Inc.Yorktown Heights,

New York

John M. StokesScience WriterSocorro, New Mexico

Salvatore TocciScience WriterEast Hampton, New York

Lab Reviewers

Christopher BarnettRichard DeCosterElizabeth RamsayerJoseph SerpicoNiles West High SchoolNiles, Illinois

Mary L. Brake, Ph.D.Physics TeacherMercy High SchoolFarmington Hills,

Michigan

Gregory PuskarLaboratory ManagerPhysics DepartmentWest Virginia UniversityMorgantown,West Virginia

Richard SorensenVernier Software &

TechnologyBeaverton, Oregon

Martin TaylorSargent-Welch/VWRBuffalo Grove, Illinois

AcademicReviewers

Mary L. Brake, Ph.D.Physics TeacherMercy High SchoolFarmington Hills,

Michigan

James C. Brown, Jr., Ph.D.Adjunct Assistant Professor

of PhysicsAustin Community CollegeAustin, Texas

Anil R Chourasia, Ph.D.Associate ProfessorDepartment of PhysicsTexas A&M University

CommerceCommerce, Texas

David S. Coco, Ph.D.Senior Research PhysicistApplied Research

LaboratoriesThe University of Texas

at AustinAustin, Texas

Thomas Joseph Connolly,Ph.D.

Assistant ProfessorDepartment of Mechanical

Engineering andBiomechanics

The University of Texas atSan Antonio

San Antonio, Texas

Brad de YoungProfessorDepartment of Physics and

Physical OceanographyMemorial UniversitySt. Johns, Newfoundland,

Canada

Bill Deutschmann, Ph.D.PresidentOregon Laser ConsultantsKlamath Falls, Oregon

Arthur A. FewProfessor of Space Physics

and EnvironmentalScience

Rice UniversityHouston, Texas

Scott Fricke, Ph.D.Schlumberger Oilfield

ServicesSugarland, Texas

Simonetta FritelliAssociate Professor of

PhysicsDuquesne UniversityPittsburgh, Pennsylvania

David S. Hall, Ph.D.Assistant Professor of

PhysicsAmherst CollegeAmherst, Massachusetts

Roy W. Hann, Jr., Ph.D.Professor of Civil

EngineeringTexas A & M UniversityCollege Station, Texas

Sally Hicks, Ph.D.ProfessorDepartment of PhysicsUniversity of DallasIrving, Texas

Robert C. HudsonAssociate Professor EmeritusPhysics DepartmentRoanoke CollegeSalem, Virginia

William Ingham, Ph.D.Professor of PhysicsJames Madison UniversityHarrisonburg, Virginia

Karen B. Kwitter, Ph.D.Professor of AstronomyWilliams CollegeWilliamstown,

Massachusetts

Phillip LaRoeProfessor of PhysicsHelena College of

TechnologyHelena, Montana

Joseph A. McClure, Ph.D.Associate Professor EmeritusDepartment of PhysicsGeorgetown UniversityWashington, DC

Ralph McGrewAssociate ProfessorEngineering Science

DepartmentBroome Community

CollegeBinghamton, New York

Clement J. Moses, Ph.D.Associate Professor of PhysicsUtica CollegeUtica, New York

Contentsiv

Alvin M. Saperstein, Ph.D.Professor of Physics; Fellow

of Center for Peace andConflict Studies

Department of Physics andAstronomy

Wayne State UniversityDetroit, Michigan

Donald E. Simanek, Ph.D.Emeritus Professor of

PhysicsLock Haven UniversityLock Haven, Pennsylvania

H. Michael Sommermann,Ph.D.

Professor of PhysicsWestmont CollegeSanta Barbara, California

Jack B. Swift, Ph.D.ProfessorDepartment of PhysicsThe University of Texas at

AustinAustin, Texas

Thomas H. Troland, Ph.D.Physics DepartmentUniversity of KentuckyLexington, Kentucky

Mary L. WhiteCoastal Ecology InstituteLouisiana State UniversityBaton Rouge, Louisiana

Jerome Williams M.S.Professor EmeritusOceanography DepartmentUS Naval AcademyAnnapolis, MD

Carol J. Zimmerman, Ph.D.Exxon Exploration

CompanyHouston, Texas

TeacherReviewers

John AdamowskiChairperson of Science

DepartmentFenton High SchoolBensenville, Illinois

John Ahlquist, M.S.Anoka High SchoolAnoka, Minnesota

Maurice BelangerScience Department HeadNashua High SchoolNashua, New Hampshire

Larry G. BrownMorgan Park AcademyChicago, Illinois

William K. Conway, Ph.D.Lake Forest High SchoolLake Forest, Illinois

Jack CooperEnnis High SchoolEnnis, Texas

William D. EllisChairman of Science

DepartmentButler Senior High SchoolButler, Pennsylvania

Diego EncisoTroy, Michigan

Ron EsmanPlano Senior High SchoolPlano, Texas

Bruce EsserMarian High SchoolOmaha, Nebraska

Curtis GoehringPalm Springs High SchoolPalm Springs, California

Herbert H. GottliebScience Education

DepartmentCity College of New YorkNew York City, New York

David J. Hamilton, Ed.D.Benjamin Franklin High

SchoolPortland, Oregon

J. Philip Holden, Ph.D.Physics Education ConsultantMichigan Dept. of

EducationLansing, Michigan

Joseph HutchinsonWichita High School EastWichita, Kansas

Douglas C. JenkinsChairman, Science

DepartmentWarren Central High SchoolBowling Green, Kentucky

David S. JonesMiami Sunset Senior

High SchoolMiami, Florida

Roger KassebaumMillard North High SchoolOmaha, Nebraska

Mervin W. Koehlinger, M.S.Concordia Lutheran High

SchoolFort Wayne, Indiana

Phillip LaRoeCentral Community CollegeGrand Island, Nebraska

William LashWestwood High SchoolRound Rock, Texas

Norman A. MankinsScience Curriculum

SpecialistCanton City SchoolsCanton, Ohio

John McGeheePalos Verdes Peninsula

High SchoolRolling Hills Estates,

California

Debra SchellAustintown Fitch High

SchoolAustintown, Ohio

Edward SchweberSolomon Schechter Day

SchoolWest Orange, New Jersey

Larry Stookey, P.E.Science

Antigo High SchoolAntigo, Wisconsin

Joseph A. TaylorMiddletown Area High

SchoolMiddletown, Pennsylvania

Leonard L. ThompsonNorth Allegheny Senior

High SchoolWexford, Pennsylvania

Keith C. TiptonLubbock, Texas

John T. VieiraScience Department HeadB.M.C. Durfee High SchoolFall River, Massachusetts

Virginia WoodRichmond High SchoolRichmond, Michigan

Tim WrightStevens Point Area Senior

High SchoolStevens Point, Wisconsin

Mary R. YeomansHopewell Valley Central

High SchoolPennington, New Jersey

G. Patrick ZoberScience Curriculum

CoordinatorYough Senior High SchoolHerminie, Pennsylvania

Patricia J. ZoberRinggold High SchoolMonongahela,

Pennsylvania

continued on page 973

Acknowledgments, continued

3CHAPTER

1

vContents

Contents

2

The Science of Physics 2

1 What is Physics? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2 Measurements in Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

The Inside Story The Mars Climate Orbiter Mission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3 The Language of Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Highlights and Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Standardized Test Prep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Skills Practice Lab Physics and Measurement . . . . . . . . . . . . . . . . . 34

Motion in One Dimension 38

1 Displacement and Velocity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

2 Acceleration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

3 Falling Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

The Inside Story Sky Diving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

PHYSICS CAREERS Science Writer . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Highlights and Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Standardized Test Prep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Skills Practice Lab Free-Fall Acceleration . . . . . . . . . . . . . . . . . . . . . . 76

CBL Lab Free-Fall Acceleration . . . . . . . . . . . . . . . . . . . . . . . . . . . 932

Advanced Topics Angular Kinematics . . . . . . . . . . . . . . . . . . . . . . . . 898

Relativity and Time Dilation . . . . . . . . . . . . . . . . 914

Two-Dimensional Motion and Vectors 80

1 Introduction to Vectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

2 Vector Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

3 Projectile Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

4 Relative Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

PHYSICS CAREERS Kinesiology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

Highlights and Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Standardized Test Prep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

Inquiry Lab Velocity of a Projectile . . . . . . . . . . . . . . . . . . . . . . . . . 116

Advanced Topics Special Relativity and Velocities . . . . . . . . . . . . . . 916

CHAPTER

CHAPTER

6CHAPTER

5CHAPTER

4CHAPTER

Contentsvi

Forces and the Laws of Motion 118

1 Changes in Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

2 Newtons First Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

The Inside Story Seat Belts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

3 Newtons Second and Third Laws . . . . . . . . . . . . . . . . . . . . . . . . 130

4 Everyday Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

The Inside Story Driving and Friction . . . . . . . . . . . . . . . . . . . . . 142



Skills Practice Lab Force and Acceleration . . . . . . . . . . . . . . . . . . . 152

CBL Lab Force and Acceleration . . . . . . . . . . . . . . . . . . . . . . . . . . 934

TimelinePhysics and Its World: 15401690 . . . . . . . . . . . . 156

Work and Energy 158

1 Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

2 Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

The Inside Story The Energy in Food . . . . . . . . . . . . . . . . . . . . . 168

3 Conservation of Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

4 Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179

PHYSICS CAREERS Roller Coaster Designer . . . . . . . . . . . . . . . . . . 182



Skills Practice Lab Conservation of Mechanical Energy . . . . . . . . 192

Advanced Topics The Equivalence of Mass and Energy . . . . . . . . . 918

Momentum and Collisions 196

1 Momentum and Impulse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198

2 Conservation of Momentum . . . . . . . . . . . . . . . . . . . . . . . . . . . 205

The Inside Story Surviving a Collision . . . . . . . . . . . . . . . . . . . . 207

3 Elastic and Inelastic Collisions . . . . . . . . . . . . . . . . . . . . . . . . . . 212

PHYSICS CAREERS High School Physics Teacher . . . . . . . . . . . . . . 221



Inquiry Lab Conservation of Momentum . . . . . . . . . . . . . . . . . . . 230

9CHAPTER

8CHAPTER

7CHAPTER

Circular Motion and Gravitation 232

1 Circular Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234

2 Newtons Law of Universal Gravitation . . . . . . . . . . . . . . . . . . . 240

The Inside Story Black Holes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243

3 Motion in Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248

4 Torque and Simple Machines . . . . . . . . . . . . . . . . . . . . . . . . . . . 254



Inquiry Lab Machines and Efficiency . . . . . . . . . . . . . . . . . . . . . . . 270

Advanced Topics Tangential Speed and Acceleration . . . . . . . . . . . 902

Rotation and Inertia . . . . . . . . . . . . . . . . . . . . . . . 904

Rotational Dynamics . . . . . . . . . . . . . . . . . . . . . . . 906

General Relativity . . . . . . . . . . . . . . . . . . . . . . . . . 920

Fluid Mechanics 272

1 Fluids and Buoyant Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274

2 Fluid Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280

3 Fluids in Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284



Advanced Topics Properties of Gases . . . . . . . . . . . . . . . . . . . . . . . . 908

Fluid Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 910


Heat 296

1 Temperature and Thermal Equilibrium . . . . . . . . . . . . . . . . . . . 298

2 Defining Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305

The Inside Story Climate and Clothing . . . . . . . . . . . . . . . . . . . . 312

3 Changes in Temperature and Phase . . . . . . . . . . . . . . . . . . . . . . 313

The Inside Story Earth-Coupled Heat Pumps . . . . . . . . . . . . . . 316

PHYSICS CAREERS HVAC Technician . . . . . . . . . . . . . . . . . . . . . . . 320



Skills Practice Lab Specific Heat Capacity . . . . . . . . . . . . . . . . . . . 328

CBL Lab Specific Heat Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . 936

Science, Technology and Society

Climatic Warming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332

viiContents

Contentsviii

10CHAPTER

11CHAPTER

12CHAPTER

Thermodynamics 334

1 Relationships Between Heat and Work . . . . . . . . . . . . . . . . . . . 336

2 The First Law of Thermodynamics . . . . . . . . . . . . . . . . . . . . . . 342

The Inside Story Gasoline Engines . . . . . . . . . . . . . . . . . . . . . . . . 348

The Inside Story Refrigerators . . . . . . . . . . . . . . . . . . . . . . . . . . . 350

3 The Second Law of Thermodynamics . . . . . . . . . . . . . . . . . . . . 352

The Inside Story Deep-Sea Air Conditioning . . . . . . . . . . . . . . . 358



Vibrations and Waves 366

1 Simple Harmonic Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368

The Inside Story Shock Absorbers . . . . . . . . . . . . . . . . . . . . . . . . 372

2 Measuring Simple Harmonic Motion . . . . . . . . . . . . . . . . . . . . 376

3 Properties of Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382

4 Wave Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389



Inquiry Lab Simple Harmonic Motion of a Pendulum . . . . . . . . . 402

Advanced Topics De Broglie Waves . . . . . . . . . . . . . . . . . . . . . . . . . . 922


Sound 406

1 Sound Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 408The Inside Story Ultrasound Images . . . . . . . . . . . . . . . . . . . . . . 410

2 Sound Intensity and Resonance . . . . . . . . . . . . . . . . . . . . . . . . . 414The Inside Story Hearing Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . 421

3 Harmonics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 422The Inside Story Reverberation . . . . . . . . . . . . . . . . . . . . . . . . . . 429

PHYSICS CAREERS Piano Tuner . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432



Skills Practice Lab Speed of Sound . . . . . . . . . . . . . . . . . . . . . . . . . 440

CBL Lab Speed of Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 938

Advanced Topics The Doppler Effect and the Big Bang . . . . . . . . . 912


Noise Pollution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 442

13CHAPTER

14CHAPTER

15CHAPTER

16CHAPTER

ixContents

Light and Reflection 444

1 Characteristics of Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 446

2 Flat Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451

3 Curved Mirrors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 455

4 Color and Polarization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469



Skills Practice Lab Brightness of Light . . . . . . . . . . . . . . . . . . . . . . 484

Refraction 486

1 Refraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 488

2 Thin Lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 494The Inside Story Cameras . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504

3 Optical Phenomena . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 506

The Inside Story Fiber Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508

PHYSICS CAREERS Optometrist . . . . . . . . . . . . . . . . . . . . . . . . . . . . 512



Skills Practice Lab Converging Lenses . . . . . . . . . . . . . . . . . . . . . . . 522

Interference and Diffraction 524

1 Interference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 526

2 Diffraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 532

3 Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 541

The Inside Story Compact Disc Players . . . . . . . . . . . . . . . . . . . . 544

PHYSICS CAREERS Laser Surgeon . . . . . . . . . . . . . . . . . . . . . . . . . . . 546



Skills Practice Lab Diffraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 554

Electric Forces and Fields 556

1 Electric Charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 558

2 Electric Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 564

3 The Electric Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 572The Inside Story Microwave Ovens . . . . . . . . . . . . . . . . . . . . . . . 579



Skills Practice Lab Electrostatics . . . . . . . . . . . . . . . . . . . . . . . . . . . 588

17CHAPTER

18CHAPTER

19CHAPTER

Electrical Energy and Current 592

1 Electric Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5942 Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6023 Current and Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 608

The Inside Story Superconductors . . . . . . . . . . . . . . . . . . . . . . . . 617

4 Electric Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 618The Inside Story Household Appliance Power Usage . . . . . . . . 622

PHYSICS CAREERS Electrician . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 624



Skills Practice Lab Current and Resistance . . . . . . . . . . . . . . . . . . . 634

Advanced Topics Electron Tunneling . . . . . . . . . . . . . . . . . . . . . . . . 924

Superconductors and BCS Theory . . . . . . . . . . . 928


Hybrid Electric Vehicles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 636

Circuits and Circuit Elements 638

1 Schematic Diagrams and Circuits . . . . . . . . . . . . . . . . . . . . . . . . 640The Inside Story Light Bulbs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 643

The Inside Story Transistors and Integrated Circuits . . . . . . . . . 646

2 Resistors in Series or in Parallel . . . . . . . . . . . . . . . . . . . . . . . . . 6473 Complex Resistor Combinations . . . . . . . . . . . . . . . . . . . . . . . . 657

The Inside Story Decorative Lights and Bulbs . . . . . . . . . . . . . . 662

PHYSICS CAREERS Semiconductor Technician . . . . . . . . . . . . . . . . 664



Inquiry Lab Resistors in Series and in Parallel . . . . . . . . . . . . . . . . 674

Magnetism 676

1 Magnets and Magnetic Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . 678The Inside Story Magnetic Resonance Imaging . . . . . . . . . . . . . 683

2 Magnetism from Electricity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6843 Magnetic Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 687

The Inside Story Television Screens . . . . . . . . . . . . . . . . . . . . . . . 688



Skills Practice Lab Magnetic Field of a Conducting Wire . . . . . . . 702

CBL Lab Magnetic Field of a Conducting Wire . . . . . . . . . . . . . 940


Electromagnetic Fields: Can They Affect Your Health? . . 704

20CHAPTER

21CHAPTER

22CHAPTER

xiContents

Electromagnetic Induction 706

1 Electricity from Magnetism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 708

The Inside Story Electric Guitar Pickups . . . . . . . . . . . . . . . . . . . 715

2 Generators, Motors, and Mutual Inductance . . . . . . . . . . . . . . 716

The Inside Story Avoiding Electrocution . . . . . . . . . . . . . . . . . . . 722

3 AC Circuits and Transformers . . . . . . . . . . . . . . . . . . . . . . . . . . 723

4 Electromagnetic Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 731

The Inside Story Radio and TV Broadcasts . . . . . . . . . . . . . . . . . 734



Skills Practice Lab Electromagnetic Induction . . . . . . . . . . . . . . . . 746


Atomic Physics 750

1 Quantization of Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 752

The Inside Story Movie Theater Sound . . . . . . . . . . . . . . . . . . . . 761

2 Models of the Atom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 762

3 Quantum Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 771



Skills Practice Lab The Photoelectric Effect . . . . . . . . . . . . . . . . . . 784

Advanced Topics Semiconductor Doping . . . . . . . . . . . . . . . . . . . . . 926


Subatomic Physics 788

1 The Nucleus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .790

2 Nuclear Decay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 797

3 Nuclear Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 807

4 Particle Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 811

PHYSICS CAREERS Radiologist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 818



Skills Practice Lab Half-Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 826

Advanced Topics The Equivalence of Mass and Energy . . . . . . . . . 918

Antimatter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 930


What Can We Do With Nuclear Waste? . . . . . . . . . . . . . . . . . . . 828

Contentsxii

Appendix A Mathematical Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 832

Appendix B Downloading Graphing Calculator Programs . . . . . . . . . . . . . . 847

Appendix C Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 848

Appendix D Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 854

Appendix E SI Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 866

Appendix F Useful Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 868

Appendix G Periodic Table of the Elements . . . . . . . . . . . . . . . . . . . . . . . . . 872

Appendix H Abbreviated Table of Isotopes and Atomic Masses . . . . . . . . . 874

Appendix I Additional Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 880

Appendix J Advanced Topics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 897

Angular Kinematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 898

Tangential Speed and Acceleration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 902

Rotation and Inertia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 904

Rotational Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 906

Properties of Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 908

Fluid Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 910

The Doppler Effect and the Big Bang . . . . . . . . . . . . . . . . . . . . . . . . . . 912

Special Relativity and Time Dilation . . . . . . . . . . . . . . . . . . . . . . . . . . 914

Special Relativity and Velocities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 916

The Equivalence of Mass and Energy . . . . . . . . . . . . . . . . . . . . . . . . . . 918

General Relativity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 920

De Broglie Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 922

Electron Tunneling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 924

Semiconductor Doping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 926

Superconductors and BCS Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . 928

Antimatter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 930

Appendix K Selected CBL Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . 932

Free-Fall Acceleration (Chapter 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 932

Force and Acceleration (Chapter 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 934

Specific Heat Capacity (Chapter 9) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 936

Speed of Sound (Chapter 12) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 938

Magnetic Field of a Conducting Wire (Chapter 19) . . . . . . . . . . . . . . . 940

Reference Section 830

Selected Answers 942

Glossary 952

Index 958

Feature Articles

The Mars Climate Orbiter Mission . . . . . . . . . . . 13

Sky Diving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Seat Belts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

Driving and Friction . . . . . . . . . . . . . . . . . . . . . . 142

The Energy in Food . . . . . . . . . . . . . . . . . . . . . . 168

Surviving a Collision . . . . . . . . . . . . . . . . . . . . . . 207

Black Holes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243

Climate and Clothing . . . . . . . . . . . . . . . . . . . . . 312

Earth-Coupled Heat Pumps . . . . . . . . . . . . . . . . 316

Gasoline Engines . . . . . . . . . . . . . . . . . . . . . . . . . 348

Refrigerators . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350

Deep-Sea Air Conditioning . . . . . . . . . . . . . . . . 358

Shock Absorbers . . . . . . . . . . . . . . . . . . . . . . . . . 372

Ultrasound Images . . . . . . . . . . . . . . . . . . . . . . . 410

Hearing Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . 421

Reverberation . . . . . . . . . . . . . . . . . . . . . . . . . . . 429

Cameras . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 504

Fiber Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508

Compact Disc Players . . . . . . . . . . . . . . . . . . . . 544

Microwave Ovens . . . . . . . . . . . . . . . . . . . . . . . . 579

Superconductors . . . . . . . . . . . . . . . . . . . . . . . . . 617

Household Appliance Power Usage . . . . . . . . . . 622

Light Bulbs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 643

Transistors and Integrated Circuits . . . . . . . . . . 646

Decorative Lights and Bulbs . . . . . . . . . . . . . . . 662

Magnetic Resonance Imaging . . . . . . . . . . . . . . . 683

Television Screens . . . . . . . . . . . . . . . . . . . . . . . . 688

Electric Guitar Pickups . . . . . . . . . . . . . . . . . . . . 715

Avoiding Electrocution . . . . . . . . . . . . . . . . . . . . 722

Radio and TV Broadcasts . . . . . . . . . . . . . . . . . . 734

Movie Theater Sound . . . . . . . . . . . . . . . . . . . . . 761

Physics and Its World: 15401690 . . . . . . . . . . . 156





Climatic Warming . . . . . . . . . . . . . . . . . . . . . . . . 332

Noise Pollution . . . . . . . . . . . . . . . . . . . . . . . . . . 442

Hybrid Electric Vehicles . . . . . . . . . . . . . . . . . . . 636

Electromagnetic Fields:Can They Affect Your Health? . . . . . . . . . . . . 704

What Can We Do With Nuclear Waste? . . . . . . 828

Science Writer . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Kinesiologist . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

Roller Coaster Designer . . . . . . . . . . . . . . . . . . 182

High School Physics Teacher . . . . . . . . . . . . . . . . 221

HVAC Technician . . . . . . . . . . . . . . . . . . . . . . . . . 320

Piano Tuner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 432

Optometrist . . . . . . . . . . . . . . . . . . . . . . . . . . . . 512

Laser Surgeon . . . . . . . . . . . . . . . . . . . . . . . . . . . 546

Electrician . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 624

Semiconductor Technician . . . . . . . . . . . . . . . . . 664

Radiologist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 818

PHYSICS CAREERSTHE INSIDE STORY

Timelines

Science Technology Society

xiiiContents

Contentsxiv

Chapter 1 Physics and Measurement . . . . . 34

Chapter 2 Free-Fall Acceleration . . . . . . . . . 76

Chapter 4 Force and Acceleration . . . . . . . 152

Chapter 5 Conservation of Mechanical Energy . . . . . . . . . . . . . . . . . . . . 192

Chapter 9 Specific Heat Capacity . . . . . . . 328

Chapter 12 Speed of Sound . . . . . . . . . . . . . 440

Chapter 13 Brightness of Light . . . . . . . . . . 484

Chapter 14 Converging Lenses . . . . . . . . . . 522

Chapter 15 Diffraction . . . . . . . . . . . . . . . . . 554

Chapter 16 Electrostatics . . . . . . . . . . . . . . . 588

Chapter 17 Current and Resistance . . . . . . 634

Chapter 19 Magnetic Field of a Conducting Wire . . . . . . . . . . . . 702

Chapter 21 Electromagnetic Induction . . . . 746

Chapter 21 The Photoelectric Effect . . . . . . 784

Chapter 22 Half-Life . . . . . . . . . . . . . . . . . . . 826

Chapter 1 Metric Prefixes . . . . . . . . . . . . . . 12

Chapter 2 Time Interval of Free Fall . . . . . . 62

Chapter 3 Projectile Motion . . . . . . . . . . . . . 97

Chapter 4 Force and Changes in Motion . . . . . . . . . . . . . . . . . . 122

Inertia . . . . . . . . . . . . . . . . . . . . . 126

Chapter 5 Mechanical Energy . . . . . . . . . . . 175

Chapter 6 Elastic and Inelastic Collisions . . . . . . . . . . . . . . . . . . 217

Chapter 7 Gravitational Field Strength . . . . . . . . . . . . . . . 245

Keplers Third Law . . . . . . . . . . . 249

Elevator Acceleration . . . . . . . . 252

Changing the Lever Arm . . . . . . 255

Chapter 9 Sensing Temperature . . . . . . . . . 298

Work and Heat . . . . . . . . . . . . . 309

Chapter 10 Entropy and Probability . . . . . . . 357

Chapter 11 Energy of a Pendulum . . . . . . . . 374

Chapter 12 Resonance . . . . . . . . . . . . . . . . . 418

A Pipe Closed at One End . . . . 425

Chapter 13 Curved Mirrors . . . . . . . . . . . . . 457

Polarization of Sunlight . . . . . . . 473

Chapter 14 Focal Length . . . . . . . . . . . . . . . 496

Prescription Glasses . . . . . . . . . 502

Periscope . . . . . . . . . . . . . . . . . . 507

Chapter 16 Polarization . . . . . . . . . . . . . . . . 562

Chapter 17 A Voltaic Pile . . . . . . . . . . . . . . . 600

A Lemon Battery . . . . . . . . . . . . 610

Energy Use in Home Appliances . . . . . . . . . . . . . . . . . 620

Chapter 18 Simple Circuits . . . . . . . . . . . . . 644

Series and Parallel Circuits . . . . 652

Chapter 19 Magnetic Field of a File Cabinet . . . . . . . . . . . . . . . . 681

Electromagnetism . . . . . . . . . . . 685

Chapter 21 Atomic Spectra . . . . . . . . . . . . . 765

Chapter 3 Velocity of a Projectile . . . . . . . 116

Chapter 6 Conservation of Momentum . . 230

Chapter 7 Machines and Efficiency . . . . . . 270

Chapter 11 Simple Harmonic Motion of a Pendulum . . . . . . . . . . . . . . 402

Chapter 18 Resistors in Series and in Parallel . . . . . . . . . . . . . . 674

Skills Practice Labs

Labs

Inquiry Labs

Chapter 2 Free-Fall Acceleration . . . . . . . . 932

Chapter 4 Force and Acceleration . . . . . . . 934

Chapter 9 Specific Heat Capacity . . . . . . . 936

Chapter 12 Speed of Sound . . . . . . . . . . . . . 938

Chapter 19 Magnetic Field of a Conducting Wire . . . . . . . . . . . . 940

CBL Labs

Quick Labs

Eye Protection

Wear safety goggles when working around chemicals,acids, bases, flames or heating devices. Contents under

pressure may become projectiles and cause serious injury.

Never look directly at the sun through any optical device oruse direct sunlight to illuminate a microscope.

Clothing Protection

Secure loose clothing and remove dangling jewelry. Donot wear open-toed shoes or sandals in the lab.

Wear an apron or lab coat to protect your clothing whenyou are working with chemicals.

Chemical Safety

Always wear appropriate protective equipment. Alwayswear eye goggles, gloves, and a lab apron or lab coat

when you are working with any chemical or chemical

solution.

Never taste, touch, or smell chemicals unless yourinstructor directs you to do so.

Do not allow radioactive materials to come into contactwith your skin, hair, clothing, or personal belongings.

Although the materials used in this lab are not hazardous

when used properly, radioactive materials can cause

serious illness and may have permanent effects.

Electrical Safety

Do not place electrical cords in walking areas or letcords hang over a table edge in a way that could cause

equipment to fall if the cord is accidentally pulled.

Do not use equipment that has frayed electrical cords orloose plugs.

Be sure that equipment is in the off position beforeyou plug it in.

Never use an electrical appliance around water or withwet hands or clothing.

Be sure to turn off and unplug electrical equipmentwhen you are finished using it.

Never close a circuit until it has been approved by yourteacher. Never rewire or adjust any element of

a closed circuit.

xvHolt Physics

If the pointer on any kind of meter moves off scale,open the circuit immediately by opening the switch.

Do not work with any batteries, electrical devices, ormagnets other than those provided by your teacher.

Heating Safety

Avoid wearing hair spray or hair gel on lab days. Whenever possible, use an electric hot plate instead of

an open flame as a heat source.

When heating materials in a test tube, always angle thetest tube away from yourself and others.

Glass containers used for heating should be made ofheat-resistant glass.

Sharp Object Safety

Use knives and other sharp instruments with extreme care.Hand Safety

Perform this experiment in a clear area. Attach massessecurely. Falling, dropped, or swinging objects can cause

serious injury.

Use a hot mitt to handle resistors, light sources, andother equipment that may be hot. Allow all equipment

to cool before storing it.

To avoid burns, wear heat-resistant gloves wheneverinstructed to do so.

Always wear protective gloves when working with an open flame, chemicals, solutions, or wild or

unknown plants.

If you do not know whether an object is hot, do nottouch it.

Use tongs when heating test tubes. Never hold a testtube in your hand to heat the test tube.

Glassware Safety

Check the condition of glassware before and after usingit. Inform your teacher of any broken, chipped, or

cracked glassware, because it should not be used.

Do not pick up broken glass with your bare hands. Placebroken glass in a specially designated disposal container.

Waste Disposal

Clean and decontaminate all work surfaces and personalprotective equipment as directed by your instructor.

Dispose of all broken glass, contaminated sharp objects,and other contaminated materials (biological and

chemical) in special containers as directed by your

instructor.

Safety Symbols

Remember that the safety symbols shown here apply to aspecific activity, but the numbered rules on the followingpages apply to all laboratory work.

Contentsxvi

Systematic, careful lab work is an essential part of

any science program because lab work is the key to

progress in science. In this class, you will practice some

of the same fundamental laboratory procedures and

techniques that experimental physicists use to pursue

new knowledge.

The equipment and apparatus you will use involve

various safety hazards, just as they do for working

physicists. You must be aware of these hazards. Your

teacher will guide you in properly using the equipment

and carrying out the experiments, but you must also

take responsibility for your part in this process. With

the active involvement of you and your teacher, these

risks can be minimized so that working in the physics

laboratory can be a safe, enjoyable process of discovery.

These safety rules always apply in the lab:

1. Always wear a lab apron and safety goggles.

Wear these safety devices whenever you are in

the lab, not just when you are working on an

experiment.

2. No contact lenses in the lab.

Contact lenses should not be worn during any

investigations using chemicals (even if you are

wearing goggles). In the event of an accident,

chemicals can get behind contact lenses and

cause serious damage before the lenses can be

removed. If your doctor requires that you wear

contact lenses instead of glasses, you should

wear eye-cup safety goggles in the lab. Ask your

doctor or your teacher how to use this very

important and special eye protection.

3. Personal apparel should be appropriate for

laboratory work.

On lab days avoid wearing long necklaces,

dangling bracelets, bulky jewelry, and bulky or

loose-fitting clothing. Loose, flopping, or

dangling items may get caught in moving parts,

accidentally contact electrical connections,

or interfere with the investigation in some

Safety In The Physics Laboratory

potentially hazardous manner. In addition,

chemical fumes may react with some jewelry,

such as pearl jewelry, and ruin them. Cotton

clothing is preferable to clothes made of wool,

nylon, or polyester. Tie back long hair. Wear shoes

that will protect your feet from chemical spills

and falling objects. Do not wear open-toed shoes

or sandals or shoes with woven leather straps.

4. NEVER work alone in the laboratory.

Work in the lab only while under the

supervision of your teacher. Do not leave

equipment unattended while it is in operation.

5. Only books and notebooks needed for the

experiment should be in the lab.

Only the lab notebook and perhaps the textbook

should be in the lab. Keep other books,

backpacks, purses, and similar items in your

desk, locker, or designated storage area.

6. Read the entire experiment before entering

the lab.

Your teacher will review any applicable safety

precautions before the lab. If you are not sure of

something, ask your teacher.

Safety in the Physics Laboratoryxvi

xviiHolt Physics

7. Heed all safety symbols and cautions written

in the experimental investigations and

handouts, posted in the room, and given

verbally by your teacher.

They are provided for a reason: YOUR SAFETY.

8. Know the proper fire-drill procedures and the

locations of fire exits and emergency

equipment.

Make sure you know the procedures to follow in

case of a fire or emergency.

9. If your clothing catches on fire, do not run;WALK to the safety shower, stand under it, and

turn it on.

Call to your teacher while you do this.

10. Report all accidents to the teacher immedi-

ately, no matter how minor.

In addition, if you get a headache, feel sick to

your stomach, or feel dizzy, tell your teacher

immediately.

11. Report all spills to your teacher immediately.

Call your teacher rather than trying to clean a

spill yourself. Your teacher will tell you if it is

safe for you to clean up the spill; if not, your

teacher will know how the spill should be

cleaned up safely.

12. Student-designed inquiry investigations, such

as the Invention Labs in the Laboratory

Experiments manual, must be approved by the

teacher before being attempted by the student.

13. DO NOT perform unauthorized experiments

or use equipment and apparatus in a manner

for which they are not intended.

Use only materials and equipment listed in the

activity equipment list or authorized by your

teacher. Steps in a procedure should only be

performed as described in the book or lab

manual or as approved by your teacher.

14. Stay alert in the lab, and proceed with caution.

Be aware of others near you or your equipment

when you are about to do something in the lab.

If you are not sure of how to proceed, ask your

teacher.

15. Horseplay and fooling around in the lab are

very dangerous.

Laboratory equipment and apparatus are not

toys; never play in the lab or use lab time or

equipment for anything other than their

intended purpose.

16. Food, beverages, chewing gum, and tobacco

products are NEVER permitted in the

laboratory.

17. NEVER taste chemicals. Do not touch

chemicals or allow them to contact areas of

bare skin.

18. Use extreme CAUTION when working with

hot plates or other heating devices.

Keep your head, hands, hair, and clothing away

from the flame or heating area, and turn the

devices off when they are not in use. Remember

that metal surfaces connected to the heated area

will become hot by conduction. Gas burners

should only be lit with a spark lighter. Make sure

all heating devices and gas valves are turned off

before leaving the laboratory. Never leave a hot

plate or other heating device unattended when it

is in use. Remember that many metal, ceramic,

and glass items do not always look hot when they

are hot. Allow all items to cool before storing.

19. Exercise caution when working with electrical

equipment.

Do not use electrical equipment with frayed or

twisted wires. Be sure your hands are dry before

using electrical equipment. Do not let electrical

cords dangle from work stations; dangling cords

can cause tripping or electrical shocks.

20. Keep work areas and apparatus clean and neat.

Always clean up any clutter made during the

course of lab work, rearrange apparatus in an

orderly manner, and report any damaged or

missing items.

21. Always thoroughly wash your hands with soap

and water at the conclusion of each

investigation.

How to Use this Textbookxviii

Internet Connect boxes in your textbook take you toresources that you can use for science projects, reports, and

research papers. Go to scilinks.org, and type in theSciLinks code to get information on a topic.

Visit go.hrw.com

Find resources and reference materials that go

with your textbook at go.hrw.com. Enter thekeyword HF6 HOME to access the home pagefor your textbook.

Be Resourceful, Use the Web

Your Roadmap for Success with Holt Physics

Get Organized

Read What to Expect and Why It Matters atthe beginning of each chapter to understandwhat you will learn in the chapter and how it applies to real situations and systems.

STUDY TIP Use the Chapter Preview outlineat the beginning of the chapter to organize yournotes on the chapter content in a way that youunderstand.

Read for Meaning

Read the Section Objectives at the beginning ofeach section because they will tell you whatyoull need to learn. Each Key Term is high-lighted in the text and defined in the margin.After reading each chapter, turn to the ChapterHighlights page and review the Key Terms andthe Key Ideas, which are brief summaries ofthe chapters main concepts. You may want todo this even before you read the chapter.

Use the charts at the bottom of the ChapterHighlights page to review important variablesymbols and diagram symbols introduced inthe chapter.

STUDY TIP If you dont understand a defi-nition, reread the page on which the term is introduced. The surrounding text should helpmake the definition easier to understand.

How to Use this Textbook

Changes in MotionSECTION 1

FORCE

You exert a on a ball when you throw or kick the ball, and you exert a

force on a chair when you sit in the chair. Forces describe the interactions

between an object and its environment.

Forces can cause accelerations

In many situations, a force exerted on an object can change the objects veloc-

ity with respect to time. Some examples of these situations are shown in

Figure 1. A force can cause a stationary object to move, as when you throw a

ball. Force also causes moving objects to stop, as when you catch a ball. A force

can also cause a moving object to change direction, such as when a baseball

collides with a bat and flies off in another direction. Notice that in each of

these cases, the force is responsible for a change in velocity with respect to

timean acceleration.

force

The SI unit of force is the newton

The SI unit of force is the newton, named after Sir Isaac Newton (16421727),

whose work contributed much to the modern understanding of force and

motion. The newton (N) is defined as the amount of force that, when acting on

a 1 kg mass, produces an acceleration of 1 m/s2. Therefore, 1 N = 1 kg 1 m/s2.

The weight of an object is a measure of the magnitude of the gravitational

force exerted on the object. It is the result of the interaction of an objects

mass with the gravitational field of another object, such as Earth. Many of the

Chapter 4120

SECTION OBJECTIVES

Describe how force affectsthe motion of an object.

Interpret and construct free-body diagrams.

Figure 1

Force can cause objects to (a) start moving, (b) stop moving,and/or (c) change direction.

force

an action exerted on an object

which may change the objects

state of rest or motion

(a) (b) (c)

CHAPTER 4

119

At General Motors Milford Proving Grounds in Michigan,

technicians place a crash-test dummy behind the steering

wheel of a new car. When the car crashes, the dummy

continues moving forward and hits the dashboard. The

dashboard then exerts a force on the dummy that acceler-

ates the dummy backward, as shown in the illustration.

Sensors in the dummy record the forces and accelerations

involved in the collision.

F

a

Forces and theLaws of Motion

WHAT TO EXPECT

In this chapter, you will learn to analyze interac-

tions by identifying the forces involved. Then,

you can predict and understand many types of

motion.

WHY IT MATTERS

Forces play an important role in engineering. For

example, technicians study the accelerations and

forces involved in car crashes in order to design

safer cars and more-effective restraint systems.

CHAPTER PREVIEW

1 Changes in Motion

Force

Force Diagrams

2 Newtons First Law

Inertia

Equilibrium

3 Newtons Second and Third Laws

Newtons Second Law

Newtons Third Law

4 Everyday Forces

Weight

The Normal Force

The Force of Friction

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xixHow to Use this Textbook

Visit Holt Online Learning

If your teacher gives you a special password to logonto the Holt Online Learning site, youll findyour complete textbook on the Web. In addition,

youll find some great learning tools and practice quizzes. Youll beable to see how well you know the material from your textbook.

Work the Problems

Sample Problems, followed by associatedPractice problems, build your reasoning andproblem-solving skills by guiding you throughexplicit example problems.

Prepare for Tests

Section Reviews and Chapter Reviews test yourknowledge of the main points of the chapter.Critical Thinking items challenge you to thinkabout the material in different ways and ingreater depth. The Standardized Test Prep thatis located after each Chapter Review helps yousharpen your test-taking abilities.

STUDY TIP Reread the Section Objectivesand Chapter Highlights when studying for a testto be sure you know the material.

Use the Appendix

Your Appendix contains a variety of resources designed to enhance your learning experience.A Mathematical Review sharpens your mathskills. The appendices Symbols, Equations, SIUnits, and Useful Tables summarize essentialproblem-solving information. AdditionalProblems provides more practice in math andproblem-solving skills. Advanced Topics allowsyou to delve deeper into areas of physics that liebeyond material presented in the chapters.

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EQUILIBRIUM

Objects that are either at rest or moving with constant velocity are said to be in

Newtons first law describes objects in equilibrium, whether they

are at rest or moving with a constant velocity. Newtons first law states one con-

dition that must be true for equilibrium: the net force acting on a body in equi-

librium must be equal to zero.

The net force on the fishing bob in Figure 6(a) is

equal to zero because the bob is at rest. Imagine that a

fish bites the bait, as shown in Figure 6(b). Because a net

force is acting on the line, the bob accelerates toward the

hooked fish.

Now, consider a different scenario. Suppose that at the

instant the fish begins pulling on the line, the person

reacts by applying a force to the bob that is equal and

opposite to the force exerted by the fish. In this case, the

net force on the bob remains zero, as shown in Fig-

ure 6(c), and the bob remains at rest. In this example, the

bob is at rest while in equilibrium, but an object can also

be in equilibrium while moving at a constant velocity.

An object is in equilibrium when the vector sum of

the forces acting on the object is equal to zero. To deter-

mine whether a body is in equilibrium, find the net

force, as shown in Sample Problem B. If the net force is

zero, the body is in equilibrium. If there is a net force, a

second force equal and opposite to this net force will

put the body in equilibrium.

equilibrium.

129Forces and the Laws of Motion

Figure 6

(a) The bob on this fishing line is at rest. (b) When the bob isacted on by a net force, it accelerates. (c) If an equal and oppositeforce is applied, the net force remains zero.

(a)

(b) (c)

equilibrium

the state in which the net force

on an object is zero

SECTION REVIEW

1. If a car is traveling westward with a constant velocity of 20 m/s, what is

the net force acting on the car?

2. If a car is accelerating downhill under a net force of 3674 N, what addi-

tional force would cause the car to have a constant velocity?

3. The sensor in the torso of a crash-test dummy records the magnitude and

direction of the net force acting on the dummy. If the dummy is thrown

forward with a force of 130.0 N while simultaneously being hit from the

side with a force of 4500.0 N, what force will the sensor report?

4. What force will the seat belt have to exert on the dummy in item 3 to

hold the dummy in the seat?

5. Critical Thinking Can an object be in equilibrium if only one force

acts on the object?

Identify the forces acting on the object and

the directions of the forces.

The string exerts 60 N on the sled in the direction that the string pulls.

The Earth exerts a downward force of 130 N on the sled.

The ground exerts an upward force of 90 N on the sled.

In a free-body diagram, only include forces acting on the object. Do notinclude forces that the object exerts on other objects. In this problem, theforces are given, but later in the chapter, you will need to identify the forceswhen drawing a free-body diagram.

Draw a diagram to represent the isolated object.

It is often helpful to draw a very simple shape with some distinguish-

ing characteristics that will help you visualize the object, as shown in

(a). Free-body diagrams are often drawn using simple squares, cir-

cles, or even points to represent the object.

Draw and label vector arrows for all external forces acting on

the object.

A free-body diagram of the sled will show all the forces acting on the

sled as if the forces are acting on the center of the sled. First, draw

and label an arrow that represents the force exerted by the string

attached to the sled. The arrow should point in the same direction

as the force that the string exerts on the sled, as in (b).

When you draw an arrow representing a force, it is important tolabel the arrow with either the magnitude of the force or a namethat will distinguish it from the other forces acting on the object.Also, be sure that the length of the arrow approximately representsthe magnitude of the force.

Next, draw and label the gravitational force, which is directed

toward the center of Earth, as shown in (c). Finally, draw and

label the upward force exerted by the ground, as shown in (d).

Diagram (d) is the completed free-body diagram of the sled

being pulled.

Fstring

P R O B L E M

The photograph at right shows a person pullinga sled. Draw a free-body diagram for this sled.The magnitudes of the forces acting on the sledare 60 N by the string, 130 N by the Earth (gravi-tational force), and 90 N upward by the ground.

S O L U T I O N

1.

2.

3.

(a)

(b)

SAMPLE PROBLEM A

Drawing Free-Body DiagramsSTRATEGY

123Forces and the Laws of Motion

FEarth

Fstring

Fground Fstring

FEarth

(c)

(d)

3

The runner in this photograph is participating in sports sci-

ence research at the National Institute of Sport and Physical

Education in France. The athlete is being filmed by a video

camera. The white reflective patches enable researchers to

generate a computer model from the video, similar to the

diagram. Researchers use the model to analyze his tech-

nique and to help him improve his performance.

CHAPTER 1

The Science ofPhysics

WHAT TO EXPECT

In this chapter, you will learn about the branch-

es of physics, the scientific method, and the use

of models in physics. You will also learn some

useful tools for working with measurements

and data.

WHY IT MATTERS

Physics develops powerful models that can be

used to describe many things in the physical

world, including the movements of an athlete

in training.

CHAPTER PREVIEW

1 What Is Physics?

The Topics of Physics

The Scientific Method

2 Measurements in Experiments

Numbers as Measurements

Accuracy and Precision

3 The Language of Physics

Mathematics and Physics

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What Is Physics?SECTION 1

THE TOPICS OF PHYSICS

Many people consider physics to be a difficult science that is far removed from

their lives. This may be because many of the worlds most famous physicists

study topics such as the structure of the universe or the incredibly small parti-

cles within an atom, often using complicated tools to observe and measure

what they are studying.

But everything around you can be described by using the tools of physics.

The goal of physics is to use a small number of basic concepts, equations, and

assumptions to describe the physical world. These physics principles can then

be used to make predictions about a broad range of phenomena. For example,

the same physics principles that are used to describe the interaction between

two planets can be used to describe the motion of a satellite orbiting Earth.

Many physicists study the laws of nature simply to satisfy their curiosity

about the world we live in. Learning the laws of physics can be rewarding just

for its own sake. Also, many of the inventions, appliances, tools, and buildings

we live with today are made possible by the application of physics principles.

Physics discoveries often turn out to have unexpected practical applications,

and advances in technology can in turn lead to new physics discoveries. Figure 1

indicates how the areas of physics apply to building and operating a car.

Chapter 14

SECTION OBJECTIVES

Identify activities and fieldsthat involve the major areaswithin physics.

Describe the processes of thescientific method.

Describe the role of modelsand diagrams in physics.

Figure 1

Without knowledge of many of theareas of physics, making cars wouldbe impossible.

Mechanics Spinning motion of the wheels, tires that provide enough friction for traction

Thermodynamics Efficient engines, use of coolants

Electromagnetism Battery, starter, headlights

Optics Headlights, rearview mirrors

Vibrations and mechanical waves Shock absorbers, radio speakers

Physics is everywhere

We are surrounded by principles of physics in our everyday lives. In fact, most

people know much more about physics than they realize. For example, when

you buy a carton of ice cream at the store and put it in the freezer at home,

you do so because from past experience you know enough about the laws of

physics to know that the ice cream will melt if you leave it on the counter.

Any problem that deals with temperature, size, motion, position, shape, or

color involves physics. Physicists categorize the topics they study in a number

of different ways. Table 1 shows some of the major areas of physics that will

be described in this book.

People who design, build, and operate sailboats, such as the ones shown in

Figure 2, need a working knowledge of the principles of physics. Designers

figure out the best shape for the boats hull so that it remains stable and float-

ing yet quick-moving and maneuverable. This design requires knowledge of

the physics of fluids. Determining the most efficient shapes for the sails and

how to arrange them requires an understanding of the science of motion and

its causes. Balancing loads in the construction of a sailboat requires knowl-

edge of mechanics. Some of the same physics principles can also explain how

the keel keeps the boat moving in one direction even when the wind is from a

slightly different direction.

5The Science of Physics

Table 1 Areas Within Physics

Name Subjects Examples

Mechanics motion and its causes, falling objects, friction,

interactions between weight, spinning

objects objects

Thermodynamics heat and temperature melting and freezing

processes, engines,

refrigerators

Vibrations and wave specific types of springs, pendulums,

phenomena repetitive motions sound

Optics light mirrors, lenses,

color, astronomy

Electromagnetism electricity, magnetism, electrical charge, cir-

and light cuitry, permanent mag-

nets, electromagnets

Relativity particles moving at any particle collisions,

speed, including very particle accelerators,

high speeds nuclear energy

Quantum mechanics behavior of submicro- the atom and its parts

scopic particles

Figure 2

Sailboat designers rely on knowl-edge from many branches of physics.

THE SCIENTIFIC METHOD

When scientists look at the world, they see a network of rules and relation-

ships that determine what will happen in a given situation. Everything you

will study in this course was learned because someone looked out at the world

and asked questions about how things work.

There is no single procedure that scientists follow in their work. However,

there are certain steps common to all good scientific investigations. These steps,

called the scientific method, are summarized in Figure 3. This simple chart is

easy to understand; but, in reality, most scientific work is not so easily separated.

Sometimes, exploratory experiments are performed as a part of the first step in

order to generate observations that can lead to a focused question. A revised

hypothesis may require more experiments.

Physics uses models that describe phenomena

Although the physical world is very complex, physicists often use to

explain the most fundamental features of various phenomena. Physics has

developed powerful models that have been very successful in describing

nature. Many of the models currently used in physics are mathematical

models. Simple models are usually developed first. It is often easier to study

and model parts of a system or phenomenon one at a time. These simple

models can then be synthesized into more-comprehensive models.

When developing a model, physicists must decide which parts of the phe-

nomenon are relevant and which parts can be disregarded. For example, lets say

you wish to study the motion of the ball shown in Figure 4. Many observations

models

Chapter 16

Make observations

and collect data that

lead to a question.

Formulate and objectively

test hypotheses

by experiments.

Interpret results,

and revise the

hypothesis if necessary.

State conclusions in

a form that can be

evaluated by others.

Figure 3

Physics, like all other sciences, isbased on the scientific method.

Figure 4

This basketball game involves greatcomplexity.

model

a pattern, plan, representation,

or description designed to show

the structure or workings of an

object, system, or concept

can be made about the situation, including the balls surroundings, size, spin,

weight, color, time in the air, speed, and sound when hitting the ground. The first

step toward simplifying this complicated situation is to decide what to study, that

is, to define the Typically, a single object and the items that immediately

affect it are the focus of attention. For instance, suppose you decide to study the

balls motion in the air (before it potentially reaches any of the other players), as

shown in Figure 5(a). To study this situation, you can eliminate everything

except information that affects the balls motion.

system.

You can disregard characteristics of the ball that have little or no effect on

its motion, such as the balls color. In some studies of motion, even the balls

spin and size are disregarded, and the change in the balls position will be the

only quantity investigated, as shown in Figure 5(b).

In effect, the physicist studies the motion of a ball by first creating a simple

model of the ball and its motion. Unlike the real ball, the model object is iso-

lated; it has no color, spin, or size, and it makes no noise on impact. Frequent-

ly, a model can be summarized with a diagram, like the one in Figure 5(b).

Another way to summarize these models is to build a computer simulation or

small-scale replica of the situation.

Without models to simplify matters, situations such as building a car or

sailing a boat would be too complex to study. For instance, analyzing the

motion of a sailboat is made easier by imagining that the push on the boat

from the wind is steady and consistent. The boat is also treated as an object

with a certain mass being pushed through the water. In other words, the color

of the boat, the model of the boat, and the details of its shape are left out of

the analysis. Furthermore, the water the boat moves through is treated as if it

were a perfectly smooth-flowing liquid with no internal friction. In spite of

these simplifications, the analysis can still make useful predictions of how the

sailboat will move.


(b)

Figure 5

To analyze the basketballs motion,(a) isolate the objects that will affectits motion. Then, (b) draw a diagramthat includes only the motion of theobject of interest.

system

a set of particles or interacting

components considered to be a

distinct physical entity for the

purpose of study

(a)

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Keyword HF6SOPX

Models can help build hypotheses

A scientific is a reasonable explanation for observationsone

that can be tested with additional experiments. The process of simplifying

and modeling a situation can help you determine the relevant variables and

identify a hypothesis for testing.

Consider the example of Galileos thought experiment, in which he

modeled the behavior of falling objects in order to develop a hypothesis about

how objects fell. At the time Galileo published his work on falling objects, in

1638, scientists believed that a heavy object would fall faster than a lighter object.

Galileo imagined two objects of different masses tied together and released

at the same time from the same height, such as the two bricks of different

masses shown in Figure 6. Suppose that the heavier brick falls faster than the

lighter brick when they are separate, as in (a). When tied together, the heavier

brick will speed up the fall of the lighter brick somewhat, and the lighter brick

will slow the fall of the heavier brick somewhat. Thus, the tied bricks should

fall at a rate in between that of either brick alone, as in (b).

However, the two bricks together have a greater mass than the heavier brick

alone. For this reason, the tied bricks should fall faster than the heavier brick,

as in (c). Galileo used this logical contradiction to refute the idea that different

masses fall at different rates. He hypothesized instead that all objects fall at the

same rate in the absence of air resistance, as in (d).

hypothesis

Models help guide experimental design

Galileo performed many experiments to test his hypothesis. To be certain he

was observing differences due to weight, he kept all other variables the same:

the objects he tested had the same size (but different weights) and were meas-

ured falling from the same point.

The measuring devices at that time were not precise enough to measure

the motion of objects falling in air. So, Galileo used the motion of a ball

rolling down a ramp as a model of the motion of a falling ball. The steeper

the ramp, the closer the model came to representing a falling object. These

ramp experiments provided data that matched the predictions Galileo made

in his hypothesis.

Chapter 18

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chapter, go to www.scilinks.org

Topic: Models in Physics

SciLinks Code: HF60977

(a) (b) (c) (d)

Galileos Thought Experiment Galileos HypothesisFigure 6

If heavier objects fell faster thanslower ones, would two bricks ofdifferent masses tied together fallslower (b) or faster (c) than theheavy brick alone (a)? Because ofthis contradiction, Galileo hypothe-sized instead that all objects fall atthe same rate, as in (d).

hypothesis

an explanation that is based on

prior scientific research or obser-

vations and that can be tested

Like Galileos hypothesis, any hypothesis must be tested in a

In an experiment to test a hypothesis, you must change one vari-

able at a time to determine what influences the phenomenon you are observing.

Galileo performed a series of experiments using balls of different weights on

one ramp before determining the time they took to roll down a steeper ramp.

The best physics models can make predictions in new situations

Until the invention of the air pump, it was not possible to perform direct tests of

Galileos model by observing objects falling in the absence of air resistance. But

even though it was not completely testable, Galileos model was used to make

reasonably accurate predictions about the motion of many objects, from rain-

drops to boulders (even though they all experience air resistance).

Even if some experiments produce results that support a certain model, at

any time another experiment may produce results that do not support the

model. When this occurs, scientists repeat the experiment until they are sure

that the results are not in error. If the unexpected results are confirmed, the

model must be abandoned or revised. That is why the last step of the scien-

tific method is so important. A conclusion is valid only if it can be verified by

other people.

experiment.

controlled


controlled experiment

an experiment that tests only

one factor at a time by using a

comparison of a control group

with an experimental group

SECTION REVIEW

1. Name the major areas of physics.

2. Identify the area of physics that is most relevant to each of the following

situations. Explain your reasoning.

a. a high school football game

b. food preparation for the prom

c. playing in the school band

d. lightning in a thunderstorm

e. wearing a pair of sunglasses outside in the sun

3. What are the activities involved in the scientific method?

4. Give two examples of ways that physicists model the physical world.

5. Critical Thinking Identify the area of physics involved in each

of the following tests of a lightweight metal alloy proposed for use in

sailboat hulls:

a. testing the effects of a collision on the alloy

b. testing the effects of extreme heat and cold on the alloy

c. testing whether the alloy can affect a magnetic compass needle

In addition to conducting experi-

ments to test their hypotheses, sci-

entists also research the work of

other scientists. The steps of this

type of research include

identifying reliable sources

searching the sources to find

references

checking for opposing views

documenting sources

presenting findings to other scien-

tists for review and discussion

Did you know?

Measurements in ExperimentsSECTION 2

NUMBERS AS MEASUREMENTS

Physicists perform experiments to test hypotheses about how changing one

variable in a situation affects another variable. An accurate analysis of such

experiments requires numerical measurements.

Numerical measurements are different from the numbers used in a math-

ematics class. In mathematics, a number like 7 can stand alone and be used in

equations. In science, measurements are more than just a number. For exam-

ple, a measurement reported as 7 leads to several questions. What physical

quantity is being measuredlength, mass, time, or something else? If it is

length that is being measured, what units were used for the measurement

meters, feet, inches, miles, or light-years?

The description of what kind of physical quantity is represented by a cer-

tain measurement is called dimension. In the next several chapters, you will

encounter three basic dimensions: length, mass, and time. Many other meas-

urements can be expressed in terms of these three dimensions. For example,

physical quantities such as force, velocity, energy, volume, and acceleration

can all be described as combinations of length, mass, and time. In later chap-

ters, we will need to add two other dimensions to our list, for temperature and

for electric current.

The description of how much of a physical quantity is represented by a cer-

tain numerical measurement depends on the units with which the quantity is

measured. For example, small distances are more easily measured in milli-

meters than in kilometers or light-years.

SI is the standard measurement system for science

When scientists do research, they must communicate the results of their experi-

ments with each other and agree on a system of units for their measurements.

In 1960, an international committee agreed on a system of standards, such as

the standard shown in Figure 7. They also agreed on designations for the fun-

damental quantities needed for measurements. This system of units is called

the Systme International dUnits (SI). In SI, there are only seven base units.

Each base unit describes a single dimension, such as length, mass, or time.

Chapter 110

SECTION OBJECTIVES

List basic SI units and thequantities they describe.

Convert measurements intoscientific notation.

Distinguish between accuracy and precision.

Use significant figures in measurements and calculations.

Figure 7

The official standard kilogram mass is a platinum-iridium cylinderkept in a sealed container at the International Bureau of Weightsand Measures at Svres, France.

The units of length, mass, and time are the meter, kilogram, and second,

respectively. In most measurements, these units will be abbreviated as m, kg,

and s, respectively.

These units are defined by the standards described in Table 2 and are

reproduced so that every meterstick, kilogram mass, and clock in the world is

calibrated to give consistent results. We will use SI units throughout this book

because they are almost universally accepted in science and industry.

Not every observation can be described using one of these units, but the

units can be combined to form derived units. Derived units are formed by

combining the seven base units with multiplication or division. For example,

speeds are typically expressed in units of meters per second (m/s).

In other cases, it may appear that a new unit that is not one of the base

units is being introduced, but often these new units merely serve as shorthand

ways to refer to combinations of units. For example, forces and weights are

typically measured in units of newtons (N), but a newton is defined as being

exactly equivalent to one kilogram multiplied by meters per second squared

(1kgm/s2). Derived units, such as newtons, will be explained throughout this

book as they are introduced.

SI uses prefixes to accommodate extremes

Physics is a science that describes a broad range of topics and requires a wide

range of measurements, from very large to very small. For example, distance

measurements can range from the distances between stars (about 100 000 000

000 000 000 m) to the distances between atoms in a solid (0.000 000 001 m).

Because these numbers can be extremely difficult to read and write, they are

often expressed in powers of 10, such as 1 1017 m or 1 109 m.

Another approach commonly used in SI is to combine the units with pre-

fixes that symbolize certain powers of 10, as illustrated in Figure 8.


Table 2 SI Standards

Unit Original standard Current standard

meter (length) distance the distance traveled by

from equator to North Pole light in a vacuum in

3.33564095 109 s

kilogram (mass) mass of 0.00 1 cubic the mass of a specific

meters of water platinum-iridium alloy

cylinder

second (time) (61

0) (6

1

0) (2

1

4) = 9 192 631 770 times

0.000 0 11 574 average the period of a radio

solar days wave emitted from a

cesium- 133 atom

1

10 000 000

Figure 8

The mass of this mosquito can beexpressed several different ways:1 105 kg, 0.0 1 g, or 10 mg.

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chapter, go to www.scilinks.org

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NIST-F1 , an atomic clock at the

National Institute of Standards and

Technology in Colorado, is one of

the most accurate timing devices

in the world. NIST-F1 is so accurate

that it will not gain or lose a second

in nearly 20 million years. As a pub-

lic service, the Institute broadcasts

the time given by NIST-F1 through

the Internet, radio stations WWV

and WWVB, and satellite signals.

Did you know?

The most common prefixes and their symbols are shown in Table 3. For

example, the length of a housefly, 5 103 m, is equivalent to 5 millimeters

(mm), and the distance of a satellite 8.25 105 m from Earths surface can be

expressed as 825 kilometers (km). A year, which is about 3.2 107 s, can also

be expressed as 32 megaseconds (Ms).

Converting a measurement from its prefix form is easy to do. You can build

conversion factors from any equivalent relationship, including those in Table 3.

Just put the quantity on one side of the equation in the numerator and the quan-

tity on the other side in the denominator, as shown below for the case of the con-

version 1 mm = 1 103 m. Because these two quantities are equal, the

following equations are also true:

1

1

0

m3

m

m = 1 and

1

1

0

m

3

m

m = 1

Thus, any measurement multiplied by either one of these fractions will be

multiplied by 1. The number and the unit will change, but the quantity

described by the measurement will stay the same.

To convert measurements, use the conversion factor that will cancel with the

units you are given to provide the units you need, as shown in the example

below. Typically, the units to which you are c

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